The present invention relates generally to the field of materials testing devices, and more particularly to a novel testing machine configured to simultaneously apply bending and torsion loads to a test specimen, the invention herein having particular utility in studies related to the mechanical properties and fracture patterns of bones.
In the studies of the strength, mechanical behavior and fracture patterns of specimens comprising whole bones, and specifically the human long bones including the radius, ulna, femur, tibia, humerus and fibula, the use of simplified mathematical models approximating bone structure are inadequate to predict responses of bone specimens to mechanical loads. Although a great deal of data on the geometry of bones exists in the literature, this information is of little use in the calculation of bone strength or in the prediction of fracture patterns of whole bone samples for practical applications because of the anisotropy and heterogeneity which characterize whole bone structure. Therefore, accurate data on the response of bones subjected to various predetermined loading conditions must necessarily be obtained experimentally.
The correlation of information gained from empirical determinations of loading characteristics and fracture patterns of bone specimens may be extremely useful to an orthopedist in determining what kind of load is responsible for a particular fracture and in providing proper treatment accordingly or in designing appropriate prostheses. Cumulative information gained through fracture studies using the osteoclast of the present invention would be useful to human factors engineers, biomedical engineers, physicians, and the like in the design of equipment, such as aircraft cockpits and ejection seat mechanisms, automobile safety equipment, and the like to avoid to the extent possible any potential trauma to which the user may be subjected.
The present invention provides a test device capable of applying bending loads or torsional loads, or any desirable combination thereof, to test specimens comprising bones. The device is uniquely configured to provide means to establish the fracture patterns which are associated with bending failures, torsional failures and failures of combined bending and torsion to provide data on the correlations between fracture patterns and the magnitudes of contributing loads, to enable the application of predetermined stress states at selected locations on the surfaces of a test bone specimen; and to provide data on the gross material behavior of bone tissue, micro-mechanical fracture topography, and fracture mode. Although the test device of the present invention is particularly suited for testing human longbones, it can be used without modification for testing a wide variety of animal bones or other structures of similar shapes. With slight modifications, structures of other types, such as vertebral column segments, short or flat bones, or the like may also be tested.
It is, therefore, an object of the present invention, to provide a novel testing device.
It is a further object of the invention to provide a testing device for simultaneously applying bending and torsion loads to a test specimen.
It is yet a further object of the invention to provide a device for applying bending and torsional loads simultaneously to a bone specimen for determining certain mechanical properties and fracture patterns of the bone.
These and other objects of the present invention will become apparent as the detailed description of certain representative embodiments thereof proceeds.